(a) Technical Field
The present disclosure relates to a system and method for periodically charging a sub-battery for an electric vehicle. More particularly, the present disclosure relates to a system and method for periodically charging a sub-battery for an electric vehicle to secure the vehicle startup performance and the sub-battery durability performance through a periodic charging of a sub-battery when a vehicle is left unattended for a long time.
(b) Background Art
Generally, electric vehicles receive a State of Charge (SOC) value of a sub-battery through an Intelligent Battery Sensor (IBS), and set an appropriate level of Low Voltage DC-DC Converter (LDC) output voltage value and then perform charging of the sub-battery. Such electric vehicles require a State of Health (SOH) value of the sub-battery to set the charging frequency and the charging time of the sub-battery. However, since there are many related parameters, such as electronic loads of a vehicle, charging/discharging frequency of the sub-battery, and temperature of the sub-battery, the SOH value of the sub-battery is difficult to accurately measure.
FIG. 1 is a flowchart illustrating a typical periodic charging method of a sub-battery for an electric vehicle. As shown in FIG. 1, the periodic charging method includes executing a preset reservation charging (S100); calculating a SOH value of a sub-battery by checking the internal temperature of the sub-battery, the electronic load of a vehicle, and the charging/discharging frequency of the sub-battery (5110); determining whether or not a SOC value of a main battery is sufficient (S120); requesting for turning-on of a main relay and operation stop of the electronic load when the SOC value of the main battery is sufficient (S130); and charging the sub-battery through an LDC operation (S140) to charge the sub-battery.
In this typical method, since all related parameters, such as the internal temperature of the sub-battery, the electronic load of a vehicle, and the charging/discharging frequency of the sub-battery, need to be measured/checked to calculate the SOH value of the sub-battery, there is a difficulty in calculating an accurate SOH value of the sub-battery, and thus the LDC output voltage value is difficult to appropriately set, causing an increase of the SOC consumption of the main battery.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the related art that is already known to a person of ordinary skill in the art.